Wireless charging is a new and upcoming technology enabling wireless charging using electro-magnetic fields. There are two basic parts. One is the transmitter and one is the reciever. The transmitter transforms the electrical current in to a electro-magnetic field, and the reciever recieves power from the field and converts back to an electrical current. It's useful in some aspects, and negative as well. Even though it's easier to charge without wires, wireless charging limits users from moving their phone while it charges, which some-what defeats the purpose of wireless charging. Wi-fi has a lmited range but it's a lot bigger than just a tiny charging mat that limits the movement of the phone. The pad also has to be plugged into the wall, so there's really no point in charging it wirelessly. It also takes about two times longer to charge wirelessly than without a wire. As of right now, wireless charging is still being improved upon and isn't better than charging with wires.
Currently, no iPhones have a normal function wireless charging (the iPhone 7's released features doesn't say anything about wireless charging either). There are rumors though of Apple still perfecting their charging technology and planning to have it included for the iPhone 8. Apple has just patented a technique of wireless charging, that might be better than current technologies. The only way for Apple products currently to wirelessly charge is with a port connected to something capable of being wireless charged. The Nexus 7 Tablet made by Google is one of the only tablets (if not the only one) capable of being wireless charged.
Starbucks introduced Powermat wireless charging to most of their locations, which began in 2014 with their stores in the San Francisco area. Starbucks has realized the importance of electronic devices, and this relates to their introduction of Wi-fi to all of their stores back in 2001. Back then, only 5% of devices had access to Wi-fi and the same thing is happening now. Only a couple of devices are capable of being wireless charged by themselves without any adapters. Soon, many devices will have the ability of being charged wirelessly.